Hi!
Stubbyness is an import property and it is not transitive. You can have an attribute that is imported and its class is a stub because the importer leaked. Now of course this situation does not make sense but this is the state of the import (we would all prefer that this imported did not leak but it is in C++ and we do not control it).
What do you mean by "leak"? I understand that a leaking importer is a bugged one. Am i right?
Cheers, Alexandre